1. Field of the Invention
This invention is related to a mobile X-ray apparatus for a circuit examination.
2. Description of the Related Art
A mobile X-ray apparatus for a circuit examination by a doctor in a conventional cordless condenser type is shown in FIG. 4a-FIG. 4c. FIG. 4a is an elevational view, FIG. 4b is a side view, and FIG. 4c is a plane view thereof. This apparatus has an X-ray tube 18, an arm 19 holding the X-ray tube 18, a collimator 7, a truck 21, a column 20 which is rotatably mounted on the truck 21, a up-down motion part which moves the arm 19 up and down along the column 20. The truck 21 has a pair of pivotable front wheels 23 and a pair of unpivotable rear wheels 22 (a right wheel 2 and a left wheel 1). This apparatus also has a X-ray controller in the truck 21. A lower disposed drive motors (a right motor 6 and a left motor 5) move the truck 21 forward or backward corresponding to manipulating an operation handle bar 14 forward and backward. The operation handle bar 14 is attached to the handle holding base 17 disposed in the truck 21.
The arm 19 has a structure for supporting and rotating the X-ray tube 18. The arm 19 also has a structure for horizontally extending and shortening itself. This apparatus is structured to keep its balance when the arm 19 moves up and down along the column 20. Therefore, the X-ray irradiation aperture of the X-ray tube 18 can be target in all directions and positions, according to a target part of an examined body.
Weight of this mobile X-ray apparatus for a circuit examination could be more than 450 kg. In that case, it is very difficult to move the truck 21 without power assist. The truck 21 generally has the rear wheels 22, which are not pivotable, and the front wheels 23 which are pivotable like casters. The rear wheels 22 are generally driven by drive motors (the right motor 6 and the left motor 5).
The truck 21 has an internal power supply with a car battery and an inverter, a high voltage transformer, a condenser, and a control circuit (not shown). The internal power supply provides 100-120V and 60 Hz power through the control circuit. An automatically programmed one-touch system is frequently used for photographing operation.
Rubber tires are used for the truck 21, and the truck 21 is designed such that it can freely move into and out of a patient""s room, an operation room or an elevator, for example. Further, the truck 21 includes a braking system, a cassette box, and accessory devices (also not shown).
It is important for a circuit examination by a doctor for the mobile X-ray apparatus to be small and light weight, and have good mobility so that the mobile X-ray apparatus can be moved to a bedroom, a technician room, an operation room, a children room, an X-ray room, an infant room, or the like in a hospital so as to take an X-ray photographing easily at these sites.
A block diagram for controlling the mobile X-ray apparatus is shown in FIG. 5. The left wheel 1 and right wheel 2 shown in the upper part of the diagram are driven by the left motor 5 and the right motor 6, respectively. The left motor 5 and the right motor 6 are independently controlled by the motor drive circuit 9. The PWM control circuit 10 carries out a switching control of the motor drive circuit 9 by pulse width modulation. The duty ratio in the switching control is controlled through signals from the CPU 35. When an operator manipulates the operation handle bar 14 of the truck 21 back and forth, signals from the left force sensor 15 and the right force sensor 16 attached to each end of the operation handle bar 14 are independently provided, as a left input Fl and a right input Fr to the CPU 35, respectively. On the other hand, signals of the left wheel rotation speed Vl and the right wheel rotation speed Vr from the left encoder 3 and the right encoder 4 which are placed at each spindle of the left wheel 1 and the right wheel 2 are provided to the CPU 35. The CPU 35 provides the PWM control circuit 10 with the duty width control signal in switching control corresponding to a back and forward input signal Ft(Fl, Fr) from the left force sensor 15 and right force sensor 16, and also a velocity signal Vt(Vl, Vr) from the left encoder 3 and the right encoder 4. The PWM control circuit 10 controls the motor drive circuit 9, and the motor drive circuit 9 controls the rotation speed of the left motor 5 and the right motor 6. The left force sensor 15 and right force sensor 16 include a flexible spring member, a Hall Effect Sensor, and a linear magnet, respectively.
The operation handle bar 14 is attached to the truck 21 through stiff but flexible spring members. The two spring members at each end of the truck 21 are hard leaf springs which make it possible to move the operation handle bar 14 back and forth a small distance corresponding to a force put on the operation handle bar 14 by its forward and backward operation. A pair of linear magnets (not shown) are attached to both ends of the operation handle bar 14.
A pair of Hall Effect (not shown) sensors are attached to the truck 21, corresponding to the linear magnets. The Hall Effect sensors are connected to a power supply (not shown in the Figures). When the Hall Effect sensor is placed at the center of the magnet, its output signal is zero level. On the other hand, when the Hall Effect sensor deviates from the center of the magnet, its output signal changes linearly between the positive maximum value and the negative maximum value. Polarity of the sensor signal corresponds to the direction of the displacement of the operation handle bar 14. Magnitude of the sensor signal is in proportion to this displacement.
The spring members make it possible to move easily the operation handle bar 14 by manipulating it back and forth and also to move it rapidly back to the neutral position just by release it.
As described above, the conventional mobile X-ray apparatus has a structure having both ends of the operation handle bar 14 being supported by laminated springs, and also that the operation handle bar 14 goes back at the neutral position, supporting its gravitative load by the laminated springs, when no operation force is added. Operation force is detected by detecting a position of magnets attached to the operation handle bar 14 by using the Hall Effect sensors. Operation force may also be detected by using strain gages stuck on the laminated springs supporting the operation handle bar 14. The apparatus is structured to move at a speed depending on operation force detected.
To use the device, an operator may push the apparatus at the operation handle bar 14 and move the apparatus to a bed side with power assist. The operator releases the operation handle bar 14 to stop the device and moves to the X-ray tube 18. Beside the X-ray tube 18, the operator may move it vertically up and down along the column 20, rotate it, and extend or shorten the arm 19 horizontally so as to aim the X-ray radiation aperture of the collimator 7 at the target part of the patient.
When a position of the X-ray tube 18 is adjusted, it may be impossible in some cases to aim it at the specified position without moving the whole apparatus again. When that happens with the conventional apparatus, the operator must go back near the apparatus body and manipulate the operation handle bar 14 again to adjust the position of the apparatus. This operation can take a long time to adjust the position of the X-ray tube 18 and also reduces examination efficiency.
Accordingly, the present invention has been made to solve the aforementioned problems. One object of the present invention is to provide a mobile X-ray apparatus for a circuit examination which makes it possible to adjust the position of the X-ray tube 18 rapidly when moving the apparatus to a position in order to photograph a patient.
To achieve the above objects, the present invention provide a mobile X-ray apparatus for a circuit examination, which includes an X-ray tube with a collimator, a mobile base having a pair of driven wheels, a holder attached and movable to the base, the holder holds the X-ray tube. A motor driver is disposed in the base which drives the wheels. An operation handle bar is disposed in the base providing a signal for driving the motor driver. An input means, separated from the handle bar, provides a signal for driving the motor driver slightly. A controller controls the motor driver according to the signal from the handle bar or the input means.
The input means may be placed at a part which can move independently from the mobile base. The part may be the collimator. The part may be the X-ray tube. The part may also be the holder.
The controller may stop the motion of the mobile base when receiving a signal from the handle bar during the receiving of a signal from the input means.
The controller may stop the motion of the mobile base when receiving a signal from the input means over a predetermined time. The predetermined time is, preferably, 10 seconds to 20 seconds.